After more disappointment at the crease and the hard word from the England selectors, all that had been missing from Michael Vaughan's week was an injury scare. So the despatch from here yesterday headed "Vaughan twists knee playing football" should really have surprised no one.

Any sentence containing the words "Vaughan" and "knee" has been a source of alarm since he developed serious problems for the first time in 2001. But, after four operations and the clock ticking down on his career, never more so than now.

So far, echoing the Government's line on swine flu, Yorkshire say there is cause for concern but not panic. "It is too early to say with certainty but there doesn't seem to be any structural problem," the county's director of cricket, Martyn Moxon, said.

"It is the right knee, the one he [Vaughan] has had problems with, and anything that happens to it will make it quite tender," he added.

"He has twisted it slightly but hopefully it will settle down. He is having ice on it and then it is a matter of rest. We have a game on Sunday in which he may play but we will have to assess it before then."

Vaughan's tweak – sustained as he warmed up with a gentle kick-about on the outfield – meant he took no part in yesterday's play. His absence was said to be no more than a precaution but it sparked speculation nonetheless.

Omitted from the two-Test series against West Indies that begins at Lord's on Wednesday, the 35-year-old former England captain is desperate to win back his place and have one last tilt at the Australians.

A weight of runs in the County Championship will give him every chance but Yorkshire have only five first-class matches between now and the first Ashes Test and Vaughan will want to sit out none. Missing tomorrow's Friends Provident Trophy match against Gloucestershire, therefore, will not be as significant as not showing up at Edgbaston for the Championship game against Warwickshire on Wednesday.

With Yorkshire in the field yesterday, Vaughan (left) had no prospect of making amends for a first-innings five. Interruptions over the first three days left a draw as the only realistic outcome and Yorkshire's opponents, still 360 behind overnight, had no plan but to bat all day, pick up some bonus points and make sure two defeats did not turn into three.

They achieved that objective, collecting a batting maximum, and gained a useful injection of confidence for good measure as both Vikram Solanki and Moeen Ali made substantial scores, the captain extending his innings beyond seven hours for the fourth double century of his career.